The N: 1 standby power supply system provides a backup power to N devices (such as switches) through an external backup power supply. Under normal circumstances, all device loads are powered primarily by their internal power source, and the standby power is close to a no-load state. If one of the devices has a power failure, the standby power supply can immediately supply power to the device. Such system only provides a backup power to only one of the faulty device, and for multiple faulty devices, the system can only supply power to the highest priority single device. Improvement in the art is preferred.